KR20190141432A - Method of calculationg soot amount trapped in gasoline particulate filter after regeration and method and system of regenerating gasoline particulate filter using the same - Google Patents

Abstract

The present invention relates to an exhaust gas postprocessing system and a control method thereof and, more specifically, to an exhaust gas postprocessing system capable of predicting a soot combustion amount of a gasoline filter based on the temperature of the front and the rear end of the gasoline filter, and a control method thereof. According to an embodiment of the present invention, the exhaust gas postprocessing system comprises: a gasoline filter to capture particulate materials contained in exhaust gas discharged by an engine; a first and a second temperature sensor arranged on the front and the rear end of the gasoline filter respectively to measure the temperature of the front end and the temperature of the rear end; a data detector to detect vehicle state data to control the gasoline filter; and a controller to perform fuel-cut based on the vehicle state data, use temperature information measured by the first and the second temperature sensor to determine whether a control condition is satisfied, and initialize a soot amount in the gasoline filter if the control condition is satisfied.

Description

METHOD OF CALCULATIONG SOOT AMOUNT TRAPPED IN GASOLINE PARTICULATE FILTER AFTER REGERATION AND METHOD AND SYSTEM OF REGENERATING GASOLINE PARTICULATE FILTER USING THE SAME}

The present invention relates to a method for calculating the residual amount of soot remaining in a gasoline filtration filter, and a method and system for regenerating a gasoline filtration filter using the same, and specifically, combustion in a gasoline filtration filter based on the amount of oxygen at the front and rear ends of the gasoline filtration filter. Predicts the amount of soot remaining, calculates the amount of soot remaining in the gasoline filtration filter from the amount of burned soot, and uses the remaining amount of soot in the gasoline filtration filter to control the regeneration of the gasoline filtration filter. And a method and system for regenerating a gasoline filtration filter using the same.

In general, gasoline direct injection (GDI) technology is being developed to improve fuel efficiency and performance in internal combustion engines. The engine to which gasoline direct injection is applied refers to an injection method in a gasoline engine that directly injects fuel into a combustion chamber without injecting fuel into an intake pipe.

This increases the air-fuel ratio around the spark plug, so that the engine can be operated even at a thin air-fuel ratio. Due to the development of gasoline direct injection technology, the generation of particulate matter (PM) is increasing due to the increase of the incomplete combustion section in the combustion chamber.

In particular, recently, particulate matter has caused great harm to the human body, and has been reported in various media as the most important main cause of air pollution.

As a means of reducing such particulate matter, a gasoline filtration filter (GPF) is installed in an exhaust system of a gasoline vehicle.

When the exhaust gas discharged from the engine passes through the gasoline filtration filter, particulate matter in the exhaust gas is collected in the gasoline filtration filter. By the way, when the amount of particulate matter collected in the gasoline filtration filter increases, the back pressure increases and the engine performance decreases.

To solve this problem, particulate matter trapped in the gasoline filtration filter should be periodically removed, and a widely used method for removing particulate matter is to burn particulate matter. This is called "playback". That is, when the amount of particulate matter (ie, the soot) trapped in the gasoline filtration filter is above a certain level, the temperature of the exhaust gas is raised above the ignition temperature to burn off the soot.

At this time, if the amount of soot trapped in the gasoline filtration filter is too large, there is a risk that the temperature of the gasoline filtration filter rises excessively during regeneration and the gasoline filtration filter is broken. Therefore, in order to control the regeneration of the soot, it is necessary to accurately estimate the amount of soot remaining in the gasoline filtration filter, and for this purpose, it is necessary to accurately predict the amount of soot burned during regeneration.

The conventional method of estimating the amount of soot burned during regeneration stores the soot combustion amount according to the temperature of the GPF, the amount of oxygen supplied to the GPF, and the flow rate of the exhaust gas flowing into the GPF, and stores the current GPF temperature and current supply. The amount of oxygen to be used and the flow rate of the current exhaust gas are input to the map data to predict the amount of soot to be burned during regeneration.

However, the actual amount of soot burning of a gasoline filtration filter may vary in various cases, such as when ash is collected a lot, when the temperature sensor value is incorrect, or when the soot is extremely unevenly collected at the edge of the gasoline filter. Affected by, there is a need to supplement the method for predicting soot burnout.

The present invention has been invented to solve the above problems, it is equipped with an oxygen sensor at the front and rear end of the gasoline filtration filter (Gasoline Particulate Filter: GPF) to calculate the remaining amount of the soot remaining in the gasoline filtration filter after regeneration. It is an object of the present invention to provide a method and system for regenerating a gasoline leisure filter using the same.

According to an embodiment of the present invention, a method of calculating a residual amount of soot remaining in a gasoline filtration filter (GPF) after regeneration may include calculating an amount of oxygen reduced as the exhaust gas passes through a gasoline filtration filter; Calculating the amount of oxygen used for soot combustion during regeneration according to the reduced amount of oxygen and the oxygen storage capacity of the gasoline filtration filter; Calculating a soot combustion amount based on the amount of oxygen used for the soot combustion; And calculating the remaining amount of soot remaining in the gasoline filtration filter based on the amount of soot collected and the amount of soot burned after the previous regeneration.

The method of calculating the soot residual amount remaining in the gasoline filtration filter after regeneration may be performed in the fuel cut state.

The method for calculating the soot residual amount remaining in the gasoline filtration filter after the regeneration may be performed when the amount of oxygen contained in the exhaust gas in front of the gasoline filtration filter in the fuel cut state is more than the set amount.

First and second oxygen sensors are installed at the front and rear ends of the gasoline filtration filter, respectively, and the amount of oxygen reduced as the exhaust gas passes through the gasoline filtration filter can be calculated based on the measured values of the first and second oxygen sensors. .

The oxygen storage capacity of the gasoline filtration filter may be determined according to the amount of oxygen storage material included in the gasoline filtration filter.

The oxygen storage material of the gasoline filtration filter may be cerium.

Regeneration method of the gasoline filtration filter according to another embodiment of the present invention comprises the steps of calculating the remaining amount of the soot during the previous regeneration; Accumulating the amount of soot trapped in the gasoline filtration filter after previous regeneration; Calculating a soot amount in the gasoline filtration filter based on the soot remaining amount and the soot trapping amount; And regenerating the gasoline filtration filter when the soot amount in the gasoline filtration filter is equal to or greater than a set amount.

The step of calculating the soot remaining amount in the previous regeneration may include calculating a reduced amount of oxygen as the exhaust gas passes through the gasoline filtration filter; Calculating the amount of oxygen used for soot combustion during regeneration according to the reduced amount of oxygen and the oxygen storage capacity of the gasoline filtration filter; Calculating a soot combustion amount based on the amount of oxygen used for the soot combustion; And calculating the remaining amount of soot remaining in the gasoline filtration filter based on the amount of soot collected and the amount of soot burned after the previous regeneration.

According to another embodiment of the present invention, a gasoline filtration filter regeneration system includes an engine configured to produce power by burning a mixture of fuel and air, and to discharge exhaust gas generated in the combustion process to the outside through an exhaust pipe; A three way catalyst (TWC) mounted on the exhaust pipe to reduce carbon monoxide, hydrocarbons, and nitrogen oxides of the exhaust gas; A gasoline filtration filter (GPF) mounted at the rear end of the three-way catalyst and collecting particulate matter contained in the exhaust gas discharged from the engine; First and second oxygen sensors mounted on exhaust pipes at the front and rear ends of the GPF and measuring oxygen concentrations of the exhaust gas flowing into the front and rear ends of the GPF; A data detector for detecting vehicle state data for controlling the GPF; And

It is determined whether the fuel is cut off based on the vehicle driving data, and the remaining amount of the soot after the regeneration of the remaining soot in the GPF is calculated using the measured values of the first and second oxygen sensors. And calculating a soot amount in the GPF based on the soot collecting amount collected in the GPF, and regenerating the GPF when the soot amount in the GPF is equal to or greater than a set amount. The remaining amount of the soot remaining in the GPF after regeneration can be calculated.

As described above, according to the present invention, the soot combustion amount may be indirectly calculated based on oxygen sensor signals at the front and rear ends of the gasoline filtration filter, and through this, the remaining soot remaining in the gasoline filtration filter may be calculated to regenerate the soot. As a result, the breakage of the gasoline filtration filter can be prevented.

1 is a schematic diagram showing a regeneration system of a gasoline filtration filter according to an embodiment of the present invention.
2 is a flowchart illustrating a method of calculating the amount of soot remaining in a gasoline filtration filter after soot regeneration according to an embodiment of the present invention.
3 is a flowchart illustrating a method of controlling soot regeneration in a gasoline filtration filter according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings and description will be described in detail the operating principle of the exhaust gas after-treatment system and its control method according to an embodiment of the present invention. However, the drawings shown below and the following detailed description relate to one preferred embodiment of various embodiments for effectively explaining the features of the present invention. Therefore, embodiments of the present invention should not be limited only to the following drawings and description.

In addition, in the following description of the embodiments of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. In addition, terms to be described below are terms defined in consideration of functions in an embodiment of the present invention, and may vary according to a user's or operator's intention or custom. Therefore, the definition should be made based on the contents throughout the specification.

In addition, the following embodiments will be used to appropriately modify, integrate, or separate terms, such that those skilled in the art to which the present invention pertains may clearly understand the technical features of the present invention. The present invention is by no means limited thereto.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic diagram illustrating a soot regeneration system in a gasoline filtration filter according to an embodiment of the present invention.

As shown in FIG. 1, the soot regeneration system of a gasoline filtration filter includes an engine 100, an exhaust pipe 110, a three-way catalyst 120, a gasoline particulate filter (GPF) 130, a first oxygen The sensor 140 includes a second oxygen sensor 145, a data detector 160, and a controller 170.

The engine 100 converts chemical energy into mechanical energy by combusting a mixture of fuel and air. That is, the engine 100 is connected to the intake manifold 103 to receive air into the combustion chamber 105, and the injector 109 is mounted in the combustion chamber 105 to inject the combustion chamber 105 into the combustion chamber 105. Here, the gasoline direct injection engine is illustrated, but is not limited thereto. That is, the engine 100 may receive a mixer from the intake manifold 103.

The engine 100 is connected to the exhaust manifold 107 so that the exhaust gas generated in the combustion process is collected in the exhaust manifold 107 and then discharged to the outside of the vehicle. The exhaust gas includes particulate matter (Particulate Matter (PM)), and the particulate matter includes soot, organic soluble substances and carbon particles.

The exhaust pipe 110 is connected to the exhaust manifold to exhaust the exhaust gas to the outside of the vehicle. The three-way catalyst 120 and the GPF 130 are mounted on the exhaust pipe 110 to remove harmful substances and particulate matter contained in the exhaust gas.

The three-way catalyst 120 is disposed in the exhaust pipe 110 to react with hydrocarbon-based compounds, carbon monoxide, and nitrogen oxides (NO _X ), which are harmful components of the exhaust gas, to convert these compounds into CO ₂ , H ₂ O, N _2, and the like. It is a catalyst. Pt / Rh, Pd / Rh or Pt / Pd / Rh systems are mainly used.

The GPF 130 is disposed on the exhaust pipe 110 and is a filter for filtering particulate matter contained in the exhaust gas.

The majority of particulate matter is a hydrocarbon called soot, which occurs when fuel is not burning properly. The GPF 130 collects particulate matter including soot by using a catalyst filter.

The GPF 130 collects and filters the soot contained in the exhaust gas discharged from the engine 100, and automatically passes through the regeneration process according to the amount of soot collected therein. This regeneration process is a process of activating the catalyst by post-injecting fuel into the exhaust stroke of the engine 100 to increase the temperature of the exhaust gas to help oxidation of the soot or to burn remaining particulate matter into ash.

The first oxygen sensor 140 is disposed in front of the GPF 130 to measure the oxygen concentration of the exhaust gas flowing into the GPF 130. The first oxygen sensor 140 provides the measured oxygen concentration information to the controller 170.

The second oxygen sensor 145 is disposed at the rear end of the GPF 130 to measure the oxygen concentration of the exhaust gas discharged from the GPF 130. The second oxygen sensor 145 provides the measured oxygen concentration information to the controller 170.

The data detector 160 measures vehicle state data for determining a driving state of the vehicle, and transmits the vehicle state data to the controller 170. The vehicle state data may include a brake pedal position value, an accelerator pedal position value, a vehicle speed, a currently engaged shift stage, a fuel injection amount and a fuel injection timing.

The controller 170 controls the engine 100 based on the oxygen concentration information measured by the first oxygen sensor 140 and the oxygen concentration information measured by the second oxygen sensor 145.

The controller 170 performs a fuel cut based on the vehicle state data.

The controller 170 calculates the amount of oxygen reduced in the GPF 130 by using the oxygen concentration measured by the first oxygen sensor 140 and the second oxygen sensor 145 when the fuel is cut off, and based on the reduced amount of oxygen, The soot combustion amount is calculated by calculating the amount of oxygen used for soot combustion. The current soot quantity in the GPF is calculated based on the soot remaining after regeneration and the soot capture amount collected in the GPF after previous regeneration. When the current soot amount in the GPF is greater than or equal to the set amount, the controller 170 controls the engine 100 to forcibly regenerate the GPF.

The set amount may vary from system to system, and in general, when the amount of soot collected in the GPF is 3 g / L or more, the GPF may be exposed to high temperatures during natural regeneration.

2 is a flowchart illustrating a method of calculating the remaining amount of soot remaining in the GPF after soot reproduction according to an embodiment of the present invention.

Referring to FIG. 2, the method for calculating the remaining amount of the soot remaining in the GPF after soot regeneration according to an embodiment of the present invention may include first and second oxygen sensors 140 disposed at the front and rear ends of the GPF 130, respectively. It is started by measuring the oxygen concentration before / after the GPF using the step (145) (S200).

In addition, the controller 170 determines whether the vehicle driving state is a fuel cutoff state based on the vehicle state data detected by the data detector 160 (S210). Since the method for determining the fuel cutoff state is well known to those skilled in the art, a description thereof will be omitted.

If the vehicle driving state is not the fuel cut state in step S210, go back to step S200 to continue measuring the oxygen concentration before / after the GPF. If the vehicle driving state is a fuel cutoff state at step S210, the controller 170 determines whether the oxygen concentration at the front end of the GPF is greater than or equal to a set value (S220). Although there is an error in the measured value of the first oxygen sensor 140, when the fuel is shut off and oxygen in the air flows into the GPF, the oxygen concentration of the front end of the GPF measured by the first oxygen sensor 140 is greater than or equal to the set value. Becomes If the oxygen concentration in front of the GPF is above the set value, it is assumed that the oxygen concentration supplied to the GPF is equal to the oxygen concentration in the atmosphere.

If the oxygen concentration in front of the GPF is less than the set value in step S220, the controller 170 determines that oxygen in the atmosphere is not supplied to the GPF, and returns to step S200 to continue measuring the oxygen concentration before and after the GPF. If the oxygen concentration of the front end of the GPF in step S220 is greater than or equal to the set value, the controller 170 calculates the amount of oxygen reduced in the GPF (S230).

A brief description of how to calculate the reduced amount of oxygen in GPF follows.

As mentioned earlier, it is assumed that the GPF is supplied with air having an oxygen concentration in the atmosphere (eg 20.6%). The second oxygen sensor 145 measures the oxygen concentration at the rear end of the GPF, and the controller 170 calculates the difference between the oxygen concentrations at the front and rear of the GPF by using the oxygen concentration supplied to the GPF and the oxygen concentration at the rear end of the GPF, and determines the exhaust flow rate. The amount of oxygen reduced in the GPF is calculated by multiplying the difference in oxygen concentration.

Thereafter, the controller 170 calculates the amount of oxygen used in soot combustion (S240). The amount of oxygen reduced in the GPF includes the amount of oxygen used for soot consumption and the amount of oxygen stored in the GPF. The amount of oxygen stored in the GPF depends on the amount of oxygen storage material contained in the GPF, which depends on the type of GPF. For example, when the oxygen storage material is cerium, some of the oxygen supplied to the GPF is stored by the Ce ₂ O ₃ + 1 / 2O _2- > CeO ₂ reaction. Therefore, the amount of oxygen stored in the GPF may be determined according to the amount of Ce contained in the GPF, or may be calculated by directly supplying oxygen to the GPF without soot and directly measuring the amount of stored oxygen. In general, the oxygen storage amount of GPF may have a value of 0.5 or more and 2g or less, which may be determined according to the type of catalyst and the degree of deterioration of GPF. Accordingly, the controller 170 may obtain the amount of oxygen used in soot combustion by subtracting the amount of oxygen stored in the GPF from the amount of oxygen reduced in the GPF.

Then, the controller 170 calculates the soot combustion amount used for soot regeneration by using the reaction formula (C + O _2- > CO ₂ ) in which carbon reacts with oxygen to produce carbon dioxide and the amount of oxygen used in the soot combustion. (S250).

For example, if the oxygen consumption is 6.36 g and the amount of oxygen stored in the catalyst of the GPF is 1.07 g, then the oxygen consumption in the soot combustion is 5.29 g, which is 6.36 g-1.07 g. Using the oxidation formula of carbon, the soot combustion rate is 1.99 g, which is 5.29 * 12/32.

Thereafter, the controller 170 subtracts the soot combustion amount obtained in step S250 from the soot collection amount before the soot regeneration to obtain the soot remaining amount after the previous regeneration (S260). The soot collection amount before soot regeneration can be obtained indirectly by inputting the temperature of the GPF before soot regeneration, the amount of oxygen supplied before soot regeneration, and the flow rate of exhaust gas before soot regeneration to the map data.

3 is a flowchart illustrating a method of controlling soot reproduction in a GPF according to an embodiment of the present invention.

Referring to FIG. 3, the method for controlling soot regeneration in a GPF according to an embodiment of the present invention begins by calculating the amount of soot remaining in the GPF after soot regeneration (S310). The soot remaining amount remaining in the GPF after soot regeneration may be a value obtained in step S260.

Thereafter, the controller 170 accumulates the amount of soot trapped in the GPF after soot reproduction (S320). The soot trapping amount collected in the GPF can be obtained indirectly by inputting the temperature of the GPF before soot regeneration, the amount of oxygen supplied before soot regeneration, and the flow rate of exhaust gas before soot regeneration into the map data.

In addition, the controller 170 calculates the soot amount in the GPF by adding the soot regeneration soot collection amount to the soot remaining after soot regeneration obtained in S260 (S330).

The controller 170 determines whether the soot amount in the GPF is greater than the set amount (S340). If the soot amount in the GPF is less than the set amount, the controller 170 returns to step S320 to accumulate the soot trapping amount after soot reproduction. If the amount of soot in the GPF is greater than the set amount in step S340, the controller 170 performs forced regeneration of the soot (S350).

The set amount of the soot amount in the GPF varies depending on the system, and in general, the set amount of the soot amount in the GPF is about 3 g / L.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art to which the present invention pertains without departing from the spirit and scope of the present invention as set forth in the claims below It will be appreciated that modifications and variations can be made.

100: engine
103: intake manifold
105: combustion chamber
107: exhaust manifold
109: injector
110: exhaust pipe
120: three-way catalyst (TWC)
130: gasoline filtration filter (GPF)
140: the first oxygen sensor
145: second oxygen sensor

Claims (9)

(a) calculating the amount of oxygen reduced as the exhaust gas passes through a Gasoline Particulate Filter (GPF);
(b) calculating the amount of oxygen used for soot combustion during regeneration according to the reduced amount of oxygen and the oxygen storage capacity of GPF;
(c) calculating the soot combustion amount based on the amount of oxygen used for the soot combustion during regeneration; And
(d) calculating the amount of soot remaining in the GPF based on the amount of soot collected prior to regeneration and the amount of soot burned;
How to calculate the remaining amount of the soot remaining in the GPF after the playback. The method of claim 1,
Step (a) to (d) is performed in the fuel cut state method for calculating the remaining soot remaining in the GPF after regeneration. The method of claim 2,
Steps (a) to (d) are performed when the oxygen concentration contained in the exhaust gas at the front end of the GPF in the fuel cut state is higher than or equal to the set concentration. How to calculate. The method according to any one of claims 1 to 3,
First and second oxygen sensors are mounted at the front and rear ends of the gasoline filtration filter, respectively.
The step (a) is performed based on the measured values of the first and second oxygen sensor, the method for calculating the remaining soot remaining in the GPF after regeneration. The method of claim 1,
The oxygen storage capacity of the GPF is determined according to the amount of oxygen storage material contained in the GPF method for calculating the residual soot remaining in the GPF after regeneration. The method of claim 5,
And the oxygen storage material is a cerium-based material. Calculating a soot remaining amount remaining in the GPF after soot regeneration;
Accumulating the amount of soot trapped in the GPF after soot regeneration;
Calculating a soot amount in GPF based on the soot remaining amount and the soot trapped amount; And
Regenerating a GPF when the soot amount in the GPF is equal to or greater than a set amount;
Including;
The method of claim 1, wherein calculating the remaining amount of the soot remaining in the GPF after the soot regeneration is calculated according to the method of claim 1. An engine that generates power by burning a mixture of fuel and air, and exhausts exhaust gas generated in the combustion process to the outside through an exhaust pipe;
A three way catalyst (TWC) mounted on the exhaust pipe to reduce carbon monoxide, hydrocarbons, and nitrogen oxides of the exhaust gas;
A gasoline filtration filter (GPF) mounted at the rear end of the three-way catalyst and collecting particulate matter contained in the exhaust gas discharged from the engine;
First and second oxygen sensors mounted on exhaust pipes at the front and rear ends of the GPF and measuring oxygen concentrations of the exhaust gas flowing into the front and rear ends of the GPF;
A data detector for detecting vehicle state data for controlling the GPF; And
Determining whether the fuel is cut off based on the vehicle driving data, calculating the remaining amount of soot after the soot regeneration remaining in the GPF using the measured values of the first and second oxygen sensors, and remaining the soot remaining after the soot regeneration. And a controller for calculating a soot amount in the GPF based on a soot trapping amount collected in the GPF, and regenerating the GPF when the soot amount in the GPF is equal to or greater than a set amount. The method of claim 8,
The controller
As the exhaust gas passes through the Gasoline Particulate Filter (GPF), it calculates the reduced amount of oxygen,
Calculating the amount of oxygen used for soot combustion during regeneration according to the reduced amount of oxygen and the oxygen storage capacity of the GPF,
The soot combustion amount is calculated based on the amount of oxygen used for the soot combustion during regeneration,
And a soot remaining amount remaining in the GPF after the regeneration based on the soot collection amount before the regeneration and the soot combustion amount.

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